<html>

<head>
<title>Assignment 4</title>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">

<script type="text/javascript" src="glMatrix-0.9.5.min.js"></script>
<script type="text/javascript" src="webgl-utils.js"></script>

<script id="shader-fs" type="x-shader/x-fragment">
    #ifdef GL_ES
    precision highp float;
    #endif

    varying vec2 vTextureCoord;
	varying float vFace;

    uniform sampler2D front;
	uniform sampler2D back;
	uniform sampler2D top;
	uniform sampler2D bottom;
	uniform sampler2D right;
	uniform sampler2D left;

    void main(void) {
        if (vFace < 0.1)
			gl_FragColor = texture2D(front, vTextureCoord);
		else if (vFace < 1.1)
			gl_FragColor = texture2D(back, vTextureCoord);
		else if (vFace < 2.1)
			gl_FragColor = texture2D(top, vTextureCoord);
		else if (vFace < 3.1)
			gl_FragColor = texture2D(bottom, vTextureCoord);
		else if (vFace < 4.1)
			gl_FragColor = texture2D(right, vTextureCoord);
		else
			gl_FragColor = texture2D(left, vTextureCoord);
		}
</script>

<script id="shader-vs" type="x-shader/x-vertex">
    attribute vec3 aVertexPosition;
    attribute vec2 aTextureCoord;
	attribute float aFace;

    uniform mat4 uMVMatrix;
    uniform mat4 uPMatrix;

    varying vec2 vTextureCoord;
	varying float vFace;

    void main(void) {
        gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
        vTextureCoord = aTextureCoord;
		vFace = aFace;
    }
</script>


<script type="text/javascript">

    var gl;

    function initGL(canvas) {
        try {
            gl = canvas.getContext("experimental-webgl");
            gl.viewportWidth = canvas.width;
            gl.viewportHeight = canvas.height;
        } catch (e) {
        }
        if (!gl) {
            alert("Could not initialise WebGL, sorry :-(");
        }
    }


    function getShader(gl, id) {
        var shaderScript = document.getElementById(id);
        if (!shaderScript) {
            return null;
        }

        var str = "";
        var k = shaderScript.firstChild;
        while (k) {
            if (k.nodeType == 3) {
                str += k.textContent;
            }
            k = k.nextSibling;
        }

        var shader;
        if (shaderScript.type == "x-shader/x-fragment") {
            shader = gl.createShader(gl.FRAGMENT_SHADER);
        } else if (shaderScript.type == "x-shader/x-vertex") {
            shader = gl.createShader(gl.VERTEX_SHADER);
        } else {
            return null;
        }

        gl.shaderSource(shader, str);
        gl.compileShader(shader);

        if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
            alert(gl.getShaderInfoLog(shader));
            return null;
        }

        return shader;
    }


    var shaderProgram;

    function initShaders() {
        var fragmentShader = getShader(gl, "shader-fs");
        var vertexShader = getShader(gl, "shader-vs");

        shaderProgram = gl.createProgram();
        gl.attachShader(shaderProgram, vertexShader);
        gl.attachShader(shaderProgram, fragmentShader);
        gl.linkProgram(shaderProgram);

        if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
            alert("Could not initialise shaders");
        }

        gl.useProgram(shaderProgram);

        shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
        gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);

        shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
        gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);
		
		shaderProgram.textureLookUpAttribute = gl.getAttribLocation(shaderProgram, "aFace");
		gl.enableVertexAttribArray(shaderProgram.textureLookUpAttribute);	

        shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
        shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
		shaderProgram.front = gl.getUniformLocation(shaderProgram, "front");
		shaderProgram.back = gl.getUniformLocation(shaderProgram, "back");
		shaderProgram.top = gl.getUniformLocation(shaderProgram, "top");
		shaderProgram.bottom = gl.getUniformLocation(shaderProgram, "bottom");
		shaderProgram.right = gl.getUniformLocation(shaderProgram, "right");
		shaderProgram.left = gl.getUniformLocation(shaderProgram, "left");
    }

    function handleLoadedTexture(texture) {
        gl.bindTexture(gl.TEXTURE_2D, texture);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, texture.image);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
        gl.bindTexture(gl.TEXTURE_2D, null);
    }


    var brian1Texture;
	var brian2Texture;
	var eric1Texture;
	var eric2Texture;
	
    function initTexture() {
    brian1Texture = gl.createTexture();
    brian2Texture = gl.createTexture();
    eric1Texture = gl.createTexture();
    eric2Texture = gl.createTexture();
    mike1Texture = gl.createTexture();
    mike2Texture = gl.createTexture();
    
    brian1Texture.image = new Image();
    brian2Texture.image = new Image();
    eric1Texture.image = new Image();
    eric2Texture.image = new Image();
    mike1Texture.image = new Image();
    mike2Texture.image = new Image();
    
    brian1Texture.image.onload = function() {
      handleLoadedTexture(brian1Texture);
    }
    brian2Texture.image.onload = function() {
      handleLoadedTexture(brian2Texture);
    }
    eric1Texture.image.onload = function() {
      handleLoadedTexture(eric1Texture);
    }
    eric2Texture.image.onload = function() {
      handleLoadedTexture(eric2Texture);
    }
    mike1Texture.image.onload = function() {
      handleLoadedTexture(mike1Texture);
    }
    mike2Texture.image.onload = function() {
      handleLoadedTexture(mike2Texture);
    }

    brian1Texture.image.src = "brian1.jpg";
    brian2Texture.image.src = "brian2.jpg";
    eric1Texture.image.src = "eric1.jpg";
    eric2Texture.image.src = "eric2.jpg";
    mike1Texture.image.src = "mike1.png";
    mike2Texture.image.src = "mike2.png";
    }


    var mvMatrix = mat4.create();
    var mvMatrixStack = [];
    var pMatrix = mat4.create();
	
	var mouseDown = false;
    var lastMouseX = null;
    var lastMouseY = null;

    var cubeRotationMatrix = mat4.create();
    mat4.identity(cubeRotationMatrix);
	
	 function handleMouseDown(event) {
        mouseDown = true;
        lastMouseX = event.clientX;
        lastMouseY = event.clientY;
    }

    function handleMouseUp(event) {
        mouseDown = false;
    }

    function handleMouseMove(event) {
        if (!mouseDown) {
            return;
        }
        var newX = event.clientX;
        var newY = event.clientY;

        var deltaX = newX - lastMouseX
        var newRotationMatrix = mat4.create();
        mat4.identity(newRotationMatrix);
        mat4.rotate(newRotationMatrix, degToRad(deltaX / 10), [0, 1, 0]);

        var deltaY = newY - lastMouseY;
        mat4.rotate(newRotationMatrix, degToRad(deltaY / 10), [1, 0, 0]);

        mat4.multiply(newRotationMatrix, cubeRotationMatrix, cubeRotationMatrix);

        lastMouseX = newX
        lastMouseY = newY;
    }

    function mvPushMatrix() {
        var copy = mat4.create();
        mat4.set(mvMatrix, copy);
        mvMatrixStack.push(copy);
    }

    function mvPopMatrix() {
        if (mvMatrixStack.length == 0) {
            throw "Invalid popMatrix!";
        }
        mvMatrix = mvMatrixStack.pop();
    }


    function setMatrixUniforms() {
        gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
        gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
    }

    function degToRad(degrees) {
        return degrees * Math.PI / 180;
    }

    var cubeVertexPositionBuffer;
    var cubeVertexIndexBuffer;
	var cubeVertexTextureCoordBuffer;
	var textureLookUpBuffer;

    function initBuffers() {
        cubeVertexPositionBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
        vertices = [
            // Front face
            -1.0, -1.0,  1.0,
             1.0, -1.0,  1.0,
             1.0,  1.0,  1.0,
            -1.0,  1.0,  1.0,

            // Back face
            -1.0, -1.0, -1.0,
            -1.0,  1.0, -1.0,
             1.0,  1.0, -1.0,
             1.0, -1.0, -1.0,

            // Top face
            -1.0,  1.0, -1.0,
            -1.0,  1.0,  1.0,
             1.0,  1.0,  1.0,
             1.0,  1.0, -1.0,

            // Bottom face
            -1.0, -1.0, -1.0,
             1.0, -1.0, -1.0,
             1.0, -1.0,  1.0,
            -1.0, -1.0,  1.0,

            // Right face
             1.0, -1.0, -1.0,
             1.0,  1.0, -1.0,
             1.0,  1.0,  1.0,
             1.0, -1.0,  1.0,

            // Left face
            -1.0, -1.0, -1.0,
            -1.0, -1.0,  1.0,
            -1.0,  1.0,  1.0,
            -1.0,  1.0, -1.0,
        ];
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
        cubeVertexPositionBuffer.itemSize = 3;
        cubeVertexPositionBuffer.numItems = 24;

        cubeVertexTextureCoordBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
        var textureCoords = [
          // Front face
          0.0, 0.0,
          1.0, 0.0,
          1.0, 1.0,
          0.0, 1.0,

          // Back face
          1.0, 0.0,
          1.0, 1.0,
          0.0, 1.0,
          0.0, 0.0,

          // Top face
          0.0, 1.0,
          0.0, 0.0,
          1.0, 0.0,
          1.0, 1.0,

          // Bottom face
          1.0, 1.0,
          0.0, 1.0,
          0.0, 0.0,
          1.0, 0.0,

          // Right face
          1.0, 0.0,
          1.0, 1.0,
          0.0, 1.0,
          0.0, 0.0,

          // Left face
          0.0, 0.0,
          1.0, 0.0,
          1.0, 1.0,
          0.0, 1.0,
        ];
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
        cubeVertexTextureCoordBuffer.itemSize = 2;
        cubeVertexTextureCoordBuffer.numItems = 24;
		
		textureLookUpBuffer = gl.createBuffer();
		gl.bindBuffer(gl.ARRAY_BUFFER, textureLookUpBuffer);
			var lookUpArray = [
				// Front face
				0.0, 0.0, 0.0, 0.0, 
				// Back face
				1.0, 1.0, 1.0, 1.0, 	
				// Back face
				2.0, 2.0, 2.0, 2.0, 
				// Back face
				3.0, 3.0, 3.0, 3.0, 
				// Back face
				4.0, 4.0, 4.0, 4.0, 
				// Back face
				5.0, 5.0, 5.0, 5.0
			];	
		gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(lookUpArray), gl.STATIC_DRAW);
		textureLookUpBuffer.itemSize = 1;
		textureLookUpBuffer.numItems = 24;

        cubeVertexIndexBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
        var cubeVertexIndices = [
            0, 1, 2,      0, 2, 3,    // Front face
            4, 5, 6,      4, 6, 7,    // Back face
            8, 9, 10,     8, 10, 11,  // Top face
            12, 13, 14,   12, 14, 15, // Bottom face
            16, 17, 18,   16, 18, 19, // Right face
            20, 21, 22,   20, 22, 23  // Left face
        ];
        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
        cubeVertexIndexBuffer.itemSize = 1;
        cubeVertexIndexBuffer.numItems = 36;
    }

    function drawScene() {
		gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

        mat4.perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0, pMatrix);

        mat4.identity(mvMatrix);

        mat4.translate(mvMatrix, [0.0, 0.0, -5.0]);
		mat4.multiply(mvMatrix, cubeRotationMatrix);
		mat4.rotate(mvMatrix, degToRad(45), [1, 0, 0]);

    gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
    gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

    gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
    gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, cubeVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
		
    gl.bindBuffer(gl.ARRAY_BUFFER, textureLookUpBuffer);
    gl.vertexAttribPointer(shaderProgram.textureLookUpAttribute, textureLookUpBuffer.itemSize, gl.FLOAT, false, 0, 0);

        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
		
		gl.activeTexture(gl.TEXTURE0);
		gl.bindTexture(gl.TEXTURE_2D, brian1Texture);
		gl.uniform1i(shaderProgram.front, 0); 
			
		gl.activeTexture(gl.TEXTURE1);
		gl.bindTexture(gl.TEXTURE_2D, brian2Texture);
		gl.uniform1i(shaderProgram.back, 1); 
			
		gl.activeTexture(gl.TEXTURE2);
		gl.bindTexture(gl.TEXTURE_2D, eric1Texture);
		gl.uniform1i(shaderProgram.top, 2); 
			
		gl.activeTexture(gl.TEXTURE3);
		gl.bindTexture(gl.TEXTURE_2D, eric2Texture);
		gl.uniform1i(shaderProgram.bottom, 3); 
			
		gl.activeTexture(gl.TEXTURE4);
		gl.bindTexture(gl.TEXTURE_2D, mike1Texture);
		gl.uniform1i(shaderProgram.right, 4); 
			
		gl.activeTexture(gl.TEXTURE5);
		gl.bindTexture(gl.TEXTURE_2D, mike2Texture);
		gl.uniform1i(shaderProgram.left, 5); 
		
        setMatrixUniforms();
        gl.drawElements(gl.TRIANGLES, cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
    }

    var lastTime = 0;

    function animate() {
        var timeNow = new Date().getTime();
        if (lastTime != 0) {
            var elapsed = timeNow - lastTime;
        }
        lastTime = timeNow;
    }


    function tick() {
        requestAnimFrame(tick);
        drawScene();
        animate();
    }


    function webGLStart() {
        var canvas = document.getElementById("assignment4-canvas");
        initGL(canvas);
        initShaders();
        initBuffers();
        initTexture();

        gl.clearColor(0.0, 0.0, 0.0, 1.0);
        gl.enable(gl.DEPTH_TEST);
		
		canvas.onmousedown = handleMouseDown;
        document.onmouseup = handleMouseUp;
        document.onmousemove = handleMouseMove;

        tick();
    }


</script>


</head>


<body onload="webGLStart();">
    <canvas id="assignment4-canvas" style="border: none;" width="500" height="500"></canvas>
</body>

</html>
